1. Field of the Invention
The present invention relates generally to devices for use in medical procedures. More particularly, this invention relates to low profile, coated guide wires for directing a catheter or other medical device through the cardiovascular system or other passage way in the human body.
2. Description of the Prior Art
The use of guide wires for positioning medical devices within the vessels of a body has been known for some time. A common current application for guide wires is an antecedent step to a percutaneous translumenal coronary angioplasty (PTCA) procedure. In this step, a guide wire is maneuvered, steered, or directed from an entry point in the arterial system, such as the femoral artery, to the site of an occlusion for example, in a coronary artery. A dilatation catheter then is advanced over the guide wire to the treatment site where the PTCA procedure is performed.
In PTCA applications, it is necessary that the guide wire have a small diameter, be flexible enough to negotiate the tortuous arterial pathways without danger of perforation, and have sufficient steerability to permit the attending physician to select the desired pathway from a number of alternatives as branches in the arterial system are encountered. The ideal guide wire, therefor is steerable, has a flexible and bendable tip, and has the ability evenly to transmit torque or translational movement from its proximal end to its distal end.
U.S. Pat. No. 4,538,622 to Samson et al. discloses a guide wire comprising an elongate flexible cylindrical element, e.g., a core wire, the elongate cylindrical element being tapered at its distal end, the distal end having two wire coils disposed thereabout. The two wire coils abut each other at their respective distal and proximal ends. The two coils comprise different materials, the more distal of the two coils comprising a radiopaque material and terminating at its extreme distal end in an atraumatic tip. In some embodiments of the invention disclosed in the '622 patent, the flexible, cylindrical element terminates within the two coil structure short of the guide wire tip and is connected to the tip by means of a safety wire or safety ribbon.
U.S. Pat. No. 4,763,647 to Gambale, and U.S. Pat. No. 4,545,390 to Leary, are similar to the Samson '622 patent discussed above in that they disclose guide wires having core wires which terminate short of the extreme distal end of the coil into which the central core wire is inserted.
U.S. Pat. No. 4,808,706 to Heilman et al. discloses a method for manufacturing catheter guidewire. In one embodiment, the guidewire of the Heilman '706 patent is developed from a coiled semi-rectangular flatwire which has been coated with a surface lubricant such as Teflon prior to winding. The Heilman et al. '706 patent is a division of an application which produced related Heilman et al. U.S. Pat. No. 4,003,369.
U.S. Pat. No. 4,895,168 to Machek discloses a moveable core guidewire assembly comprising a wire wound cylindrical casing having a distal closed end and a proximal open end. Between the proximal and distal ends of the cylindrical casing is a resilient moveable core wire. The assembly further includes a plastic safety cover coextensive with and surrounding the wire wound cylindrical casing.
U.S. Pat. No. 4,724,846 to Evans, III discloses a catheter guide wire assembly that has a combined core and safety wire extending longitudinally between its proximal and distal ends. A wound wire is positioned around the combined core and safety wire and follows the countour thereof. The combined core and safety wire of the Evans, III '846 patent has proximal, intermediate, and distal segments with different diameters.
None of the above patents or other references alone or in combination, disclose or suggest the present invention.